The present invention relates to timing corrections, and more particularly to a component television timing corrector for maintaining time alignment between the three components of a color television signal to achieve optimum picture quality.
Typically color television signals are composed of three components. Even in the standard composite broadcast format, such as NTSC, PAL or SECAM, at some point some signal processing is done in component form. The component form is usually a luminance component Y and two color difference components B-Y, R-Y. Component signal processing invariably results in differential timing errors between the components as each component is processed separately, resulting in picture distortions to a viewer. Although the luminance component often includes a sync pulse for timing reference, the color components often do not. Prior attempts to compensate for the difference in timing among the various component signal paths have been to transmit a test signal along the different signal paths and compare the outputs, adjusting a delay device in one path to assure coincidence of the output test signals. Such a system is described in co-pending U.S. application Ser. No. 722,943 filed Apr. 12, 1985 by Bruce J. Penney entitled "Method and Apparatus for Measuring Delay and/or Gain Difference". This requires a separate test signal generator to generate the test signal, and does not compensate for drift in the signal processing paths between calibrations.
What is desired is a component television timing corrector which is self-calibrating and can maintain a constant correction of the component signal path timing differences to compensate for drift.